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Determining Blast Loads on Building Structures

September 21, 2016

Our Weidlinger Protective Design practice uses a variety of tools—including internally developed software modeling packages—to determine the potential effects of blast loads on building structures. A variety of toolsets and approaches allow our experts to best calculate a structure’s performance when subjected to a blast. Our tools can account for such blast phenomena as shockwaves, gas pressure loads, fragmentation and thermal radiation.

Weidlinger Protective Design’s 65 years of experience in providing physical security analysis, advice and design to architects, building owners, developers and public agencies makes us the premier expert in protective design services. We assess vulnerability to multiple hazards and provide balanced and economical mitigation for every type of structure.

Much of our R&D work involves writing and maintaining computational software, and developing fast-running tools for modeling blast, shock and impact loadings. These tools can be used to analyze military and civilian structures subjected to terrorist and conventional weapons loading, including in air and underwater. Over the years, our clients have included U.S. Navy’s NAVSEA and ONR Office of Naval Research, NATO, the U.K. Royal Navy, the U.S. Defense Threat Reduction Agency, the U.S. Air Force and the U.S. Department of Homeland Security.

The CFD software developed by our U.K. Thornton Tomasetti Defence Ltd. office is at the cutting edge of technology utilizing the vast computing power of modern day graphics cards to accelerate project turnaround times and enhance the fidelity of today’s predictive toolsets. Finite element analysis software, such as our internal state-of-the-art modeling software NLFLEX, may also be run in parallel with CFD to observe coupled structure-shock interactions.

The video above shows a coupled computational fluid dynamics (CFD) and glazing element blast simulation of the 2011 attack on the Office of the Prime Minister in Oslo, Norway. The contours indicate the extreme peak dynamic pressures at the leading edge of the shock front, shown in red, which decreases rapidly as the shockwave expands. Failure of the windows in the building façade in response to this shock front is graphically depicted over time by the transition from blue (undamaged) to their removal (when they fail) with subsequent loading on the floors and internals of the building. Coupled simulations help capture phasing, local response and higher order effects.